1. Technical Field of the Invention
The invention relates to methods, apparatus, and signals used in channel coding and decoding, and, in particular embodiments to methods, apparatus and signals for use with turbo and turbo-trellis encoding and decoding for communication channels.
2. Description of Related Art
A significant amount of interest has recently been paid to channel coding. For example a recent authoritative text states: “Channel coding refers to the class of signal transformations designed to improve communications performance by enabling the transmitted signals to better withstand the effects of various channel impairments, such as noise, interference, and fading. These signal-processing techniques can be thought of as vehicles for accomplishing desirable system trade-offs (e.g., error-performance versus bandwidth, power versus bandwidth). Why do you suppose channel coding has become such a popular way to bring about these beneficial effects? The use of large-scale integrated circuits (LSI) and high-speed digital signal processing (DSP) techniques have made it possible to provide as much as 10 dB performance improvement through these methods, at much less cost than through the use of most other methods such as higher power transmitters or larger antennas.” From “Digital Communications” Fundamentals and Applications Second Edition by Bernard Sklar, page 305 @ 2001 Prentice Hall PTR.
Stated differently, improved coding techniques may provide systems that can operate at lower power or may be used to provide higher data rates.